/*********
  Rui Santos
  Complete project details at https://RandomNerdTutorials.com/esp32-hc-sr04-ultrasonic-arduino/
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files.
  
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
*********/

const int trigPin = 5;
const int echoPin = 18;

//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

#define REDLEDS1_Pin 32
#define REDLEDS2_Pin 2
#define GREENLEDS1_Pin 14
#define GREENLEDS2_Pin 4

long duration;
float distanceCm;
float distanceInch;

void setup() {
  Serial.begin(115200); // Starts the serial communication
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input
  pinMode(REDLEDS1_Pin, OUTPUT);
  pinMode(GREENLEDS1_Pin, OUTPUT);
  pinMode(REDLEDS2_Pin, OUTPUT);
  pinMode(GREENLEDS2_Pin, OUTPUT);
}

void loop() {
  // Clears the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  duration = 20000;
  // Calculate the distance
  distanceCm = duration * SOUND_SPEED/2;
  
  // Convert to inches
  distanceInch = distanceCm * CM_TO_INCH;

  if (distanceCm <= 300) 
      {
        digitalWrite(REDLEDS1_Pin, HIGH);
        digitalWrite(REDLEDS2_Pin, HIGH);
        digitalWrite(GREENLEDS1_Pin, LOW);
        digitalWrite(GREENLEDS2_Pin, LOW);
      }
      else
      {
      digitalWrite(REDLEDS1_Pin, LOW);
      digitalWrite(GREENLEDS1_Pin, HIGH);
      digitalWrite(REDLEDS2_Pin, LOW);
      digitalWrite(GREENLEDS2_Pin, HIGH);  
      }

  
  // Prints the distance in the Serial Monitor
  Serial.print("Duration : ");
  Serial.println(duration);
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  Serial.print("Distance (inch): ");
  Serial.println(distanceInch);
  
  delay(1000);
}